Optimal treatment of complicated skin and skin structure infections

Topical Administration of Drugs Incorporated in Carriers Containing Phospholipid Soft Vesicles for the Treatment of Skin Medical Conditions

This review focuses on the improved topical treatment of various medical skin conditions by the use of drugs delivered from carriers containing phospholipid soft vesicles. Topical drug delivery has many advantages over other ways of administration, having increased patient compliance, avoiding the first-pass effect following oral drug administration or not requesting multiple doses administration. However, the skin barrier prevents the access of the applied drug, affecting its therapeutic activity. Carriers containing phospholipid soft vesicles are a new approach to enhance drug delivery into the skin and to improve the treatment outcome. These vesicles contain molecules that have the property to fluidize the phospholipid bilayers generating the soft vesicle and allowing it to penetrate into the deep skin layers. Ethosomes, glycerosomes and transethosomes are soft vesicles containing ethanol, glycerol or a mixture of ethanol and a surfactant, respectively. We review a large number of publications on the research carried out in vitro, in vivo in animal models and in humans in clinical studies, with compositions containing various active molecules for treatment of skin medical conditions including skin infections, skin inflammation, psoriasis, skin cancer, acne vulgaris, hair loss, psoriasis and skin aging.

Vancomycin Use in Children and Neonates across Three Decades: A Bibliometric Analysis of the Top-Cited Articles

Vancomycin is frequently prescribed in pediatrics, especially in intensive care unit settings, to treat Gram-positive bacterial infections. This work aims to collect the top-cited articles of pediatric and infectious diseases areas to gather the current evidence and gaps of knowledge on the use of vancomycin in these populations. The most relevant journals reported in the "pediatrics" and "infectious diseases" categories of the 2019 edition of Journal Citation Reports were browsed. Articles with more than 30 citations and published over the last three decades were collected. A bibliometric analysis was performed and 115 articles were retrieved. They were published in 21 journals, with a median impact factor of 4.6 (IQR 2.9-5.4). Sixty-eight of them (59.1%) belonged to "infectious diseases" journals. The most relevant topic was "bloodstream/complicated/invasive infections", followed by "antibiotic resistance/MRSA treatment". As for population distribution, 27 articles were on children only and 27 on neonates, most of which were from intensive care unit (ICU) settings. The current literature mainly deals with vancomycin as a treatment for severe infections and antibiotic resistance, especially in neonatal ICU settings. Lately, attention to new dosing strategies in the neonatal and pediatric population has become a sensible topic.

Locally isolated broad host-range bacteriophage kills methicillin-resistant Staphylococcus aureus in an in vivo skin excisional wound model in mice

From the perspective of an ever-increasing multidrug resistance among bacterial pathogens, bacteriophages are receiving renewed interest as potential alternative to antibiotics. We investigated the potential of a locally isolated species-specific phage against Staphylococcus aureus infection in a skin excisional wound model in mice. A significant time-dependent increase (P < 0.05) in wound healing was observed in the phage-treated mice groups. The animals treated with the phage ΦDMSA-2 exhibited a faster re-epithelialization and faster tissue re-modelling. Bacterial load in the infected tissue in all phage-treated groups diminished. The mean ± SD CFU per ml decreased from 3.3 × 10⁸ ± 3.5 × 10⁶ at day 1-1.43 × 10³ ± 8.48 × 10² at day 16 (P < 0.05). The highest reduction in the bacterial load was observed in G5 (povidine-iodine treated) and G6 (povidine iodine + phage 10⁷ PFU) groups as no bacterial counts were detected by day 12 in both groups. Interestingly, group G3, which was treated with a lower phage concentration (5 × 10⁶ PFU), resulted in total clearing of the inoculated bacteria by day 16; while bacterial counts were still detected by that time in group G4, which was treated with a higher phage concentration of 10⁷ PFU. Animals from phage-treated group G3 survived 100%, while those from the infected wound control group survived at a rate of 34% at day 9 and reached 0% by the end of day 22 (P < 0.001). The data from this study convincingly showed that phage treatment of the S. aureus-infected wounds resulted in a faster wound healing and a 100% survival of the animals. The results emphasize the utility of locally isolated species-specific phages in treatment against multidrug-resistant MRSA infections.

The clinical and economic burden of community-onset complicated skin and skin structure infections in Korea

BACKGROUND/AIMS

To investigate epidemiologic characteristics, clinical and economic burdens, and factors associated with mortality in complicated skin and skin structure infection (cSSSI) patients in Korea.

METHODS

A retrospective, observational, nationwide study was conducted between April to July 2012 at 14 tertiary-hospitals in Korea. Eligible patients were hospitalized adults with community acquired cSSSI, who underwent surgical intervention and completed treatment between November 2009 and October 2011. Data on demography, clinical characteristics, outcomes and medical resource utilization were collected through medical record review. Direct medical costs were calculated by multiplying quantities of resources utilized by each unit price in Korea.

RESULTS

Of 473 patients enrolled, 449 patients (except 24 patients with no record on surgical intervention) were eligible for analysis. Microbiological testing was performed on 66.1% of patients and 8.2% had multiple pathogens. Among culture confirmed pathogens (n = 297 patients, 340 episodes), 76.2% were gram-positive (Staphylococcus aureus; 41.2%) and 23.8% were gram-negative. The median duration of hospital stay was 16 days. Among treated patients, 3.3% experienced recurrence and 4.2% died in-hospital. The mean direct medical costs amounted to $4,195/ person, with the greatest expenses for hospitalization and antibiotics. The in-hospital mortality and total medical costs were higher in combined antibiotics therapy than monotherapy (p < 0.05). Charlson's comorbidity index ≥ 3, standardized early warning scoring ≥ 4, sub-fascia infections and combined initial therapy, were all found to be associated with higher mortality.

CONCLUSION

Korean patients with community-onset cSSSI suffer from considerable clinical and economic burden. Efforts should be made to reduce this burden through appropriate initial treatment.

Structural deformation in pathogenic bacteria cells caused by marine fungal metabolites: An in vitro investigation

Over the past 50 years, fungal natural products have revolutionized medicine, yielding drugs which have enormous therapeutic potential. The aim of this study was to investigate the probable effect of marine fungal natural products on various skin pathogens. Initially, seventy natural extracts obtained from 35 different marine fungal strains were analysed by the agar well diffusion and broth micro dilution assay for their antibacterial action against six human skin pathogens. The minimum inhibitory effects of all active fungal methanolic extracts on targeted pathogens were observed between 90 and 99% at the concentration of 1 mg/mL. The highest activity was recorded by fungal strains belonging to genera Penicillium, Emericellopsis and Simplicillium. Thereafter, possible effects on target bacterial cells were studied by scanning electron microscopy which show significant destruction and structural deformation in the bacterial cell wall. The results of the present study provided good evidence that the studied marine fungi can be a potential source of natural antibacterial agents against skin bacterial pathogens.

Epidemiology and Outcomes of Complicated Skin and Soft Tissue Infections among Inpatients in Southern China from 2008 to 2013

Complicated skin and soft tissue infections (cSSTI) are some of the most commonly treated infections in hospitals, and place heavy economic burdens on patients and society. Here we report the findings from an analysis of cSSTI based on a retrospective study which was conducted within the Chinese inpatient population. We focused our research on the analysis of the patient population, antibiotic treatment, clinical outcome and economic burden. The study population comprised 527 selected patients hospitalized between 2008 and 2013. Among the hospitalizations with microbiological diagnoses, 61.41% (n = 113) were diagnosed as infected with Gram-positive bacteria, while 46.20% (n = 85) were infected with Gram-negative bacteria. The most commonly found Gram-positive bacteria was Staphylococcus aureus (40.76%, n = 75), and the most common Gram-negative bacteria was Escherichia coli (14.13%, n = 26). About 20% of the Staphylococcus aureus were methicillin-resistant. The resistance rate of isolated Staphylococcus aureus or Escherichia coli to penicillin was around 90%; in contrast, the resistance rate to vancomycin, linezolid or imipenem was low (<20%). A large percentage of patients were treated with cephalosporins and fluoroquinolones, while vancomycin and imipenem were also included to treat drug-resistant pathogens. Over half of the hospitalizations (58.43%, n = 336) experienced treatment modifications. The cost to patients with antibiotic modifications was relatively higher than to those without. In conclusion, our study offers an analysis of the disease characteristics, microbiological diagnoses, treatment patterns and clinical outcomes of cSSTI in four hospitals in Guangdong Province, and sheds lights on the current clinical management of cSSTI in China.

Clinical and Economic Consequences of Failure of Initial Antibiotic Therapy for Hospitalized Patients With Complicated Skin and Skin-Structure Infections

Objective.

To estimate the consequences of failure of initial antibiotic therapy for patients with complicated skin and skin-structure infections.

Design.

Retrospective cohort study.

Setting.

Large US multihospital database.

Patients.

We identified a total of 47,219 patients (age 18 years or older) who were admitted to the hospital for complicated skin and skin-structure infections from April 1, 2003, through March 31, 2004, and who received intravenous antibiotics during the first 2 hospital-days (ie, initial antibiotic therapy). Failure of therapy was defined as drainage, debridement, or receipt of other intravenous antibiotics at any subsequent time (except for changes to narrower-spectrum agents or any therapy change immediately before discharge). Predictors of failure of antibiotic therapy and mortality were examined using multivariate logistic regression. Analysis of covariance was used to estimate the impact of treatment failure on duration of intravenous antibiotic therapy, length of stay, and total inpatient charges.

Results.

For 10,782 admitted patients (22.8%), there was evidence of failure of initial antibiotic therapy. In multivariate analyses, treatment failure was associated with receipt of vasoactive medications during the first 2 hospital-days (odds ratio [OR], 1.66 [95% confidence interval {CI}, 1.19-2.31]), initiation of antibiotic therapy in the intensive care unit (OR, 1.53 [95% CI, 1.28-1.84]), and the patient's Charlson comorbidity index (OR per 1-point increase, 1.06 [95% CI, 1.04-1.08]); treatment failure was also was associated with a 3-fold increase in mortality (OR, 2.91 [95% CI, 2.34-3.62]). Compared with patients for whom initial treatment was successful, patients who experienced treatment failure received intravenous antibiotic therapy for a mean of 5.7 additional days, were hospitalized for a mean of 5.4 additional days, and incurred a mean of $5,285 (in 2003 dollars) in additional inpatient charges (all P <.01).

Conclusion.

Failure of initial antibiotic therapy in the treatment of complicated skin and skin-structure infections is associated with significantly worse clinical and economic outcomes.

Using daptomycin in hospitalised patients with cSSTI caused by Staphylococcus aureus has an impact on costs

BACKGROUND

The aim was to assess the cost impact of daptomycin compared to vancomycin treatment in patients hospitalised for complicated skin and soft-tissue infection (cSSTI) with suspected methicillin-resistant Staphylococcus aureus infection in the UK.

METHODS

A decision model was developed to estimate the costs associated with cSSTI treatment. Data on efficacy, treatment duration and early discharge from published clinical trials were used, with data gaps on standard clinical practice being filled by means of clinician interviews.

RESULTS

Total health-care costs per patient were GBP 6,214 and GBP 6,491 for daptomycin and vancomycin, respectively. A sensitivity analysis suggested that modifying the parameters within a reasonable range does not impact on the conclusion that the higher cost of daptomycin is likely to be offset by lower costs of monitoring and hospitalisation.

CONCLUSIONS

This study demonstrates that daptomycin not only provides an alternative treatment for multiple resistant infections, but may also reduce National Health Service costs.

Role of linezolid in the treatment of complicated skin and soft tissue infections

Staphylococcus aureus is the most common cause of complicated skin and soft tissue infections (cSSTIs). Antibiotic choices for these infections continue to evolve. History has seen penicillin progress to antistaphylococcal penicillins and cephalosporins, but these drugs are now giving way to drugs that are effective against methicillin-resistant S. aureus (MRSA). While vancomycin has been the gold standard to treat MRSA infections, newer therapeutic options have been developed over the last 5 years. These include quinupristin-dalfopristin, daptomycin, tigecycline and linezolid, which is the focus for this review. Linezolid is efficacious in the treatment of cSSTIs (including diabetic foot infections) caused by Gram-positive organisms (including MRSA), with a well-defined safety profile and straightforward dosing. It is also approved for nosocomial pneumonia, community-acquired pneumonia and uncomplicated skin and skin structure infections. Linezolid has an oral and parenteral formulation, which are equivalent. The oral formulation has the potential to offer economic benefits as compared with other therapies. Currently, there are only a few new antibiotics in development with MRSA activity. The proper use of all antibiotics, including these newer agents, is increasingly important if we are to slow the evolution of microbial resistance.

Sequential intravenous/oral moxifloxacin monotherapy for complicated skin and skin structure infections: a meta-analysis of randomised controlled trials

OBJECTIVES

The presumed superiority of moxifloxacin for the treatment of complicated skin and skin structure infections (cSSSIs) is based on laboratory data, but has not yet been established on clinical grounds. The aim of this meta-analysis was to evaluate the efficacy and safety of sequential intravenous (i.v.)/oral (p.o.) moxifloxacin monotherapy for the treatment of cSSSIs.

METHODS

Randomised controlled trials (RCTs) published prior to November 2012 were systematically retrieved from PubMed, MEDLINE, EMBASE, ScienceDirect, ClinicalTrials.gov and the Cochrane Central Register of Controlled Trials. Finally, a meta-analysis of all RCTs eligible for inclusion criteria was performed.

RESULTS

Three studies that enrolled 2255 patients were included in the meta-analysis. There were no statistically significant differences between patients given moxifloxacin and those given other antibiotics with regard to clinical success rate [1667 patients, odds ratio (OR) = 0.83, 95% confidence interval (CI) 0.63 to 1.09, p = 0.18], bacteriological success rate (bacteriological success rates: 1502 patients, OR = 0.90, 95% CI 0.68-1.18, p = 0.45) or mortality (2207 patients, OR = 1.96, 95% CI 0.79-4.88, p = 0.15). Significantly, more overall adverse events (AEs) were associated with the use of moxifloxacin than with other antibiotics (2207 patients, OR = 1.21, 95%CI 1.00-1.45, p = 0.04). However, there was no statistically significant difference in the occurrence of drug-related AEs, serious AEs or serious drug-related AEs between patients given moxifloxacin and those given other antibiotics.

CONCLUSION

Sequential i.v./p.o. moxifloxacin monotherapy is an effective and relatively safe option for the treatment of cSSSIs. Other benefits of moxifloxacin may make it a more viable option compared with the currently used regimens.

Clinical response at Day 3 of therapy and economic outcomes in hospitalized patients with acute bacterial skin and skin structure infection (ABSSSI)

OBJECTIVE

The FDA recently issued guidance for the types of infections that should be included in trials to support an indication for antibacterial treatment. The latest FDA guidance recommends assessing response to drug therapy at 48 to 72 hours as the primary endpoint in clinical trials. This study evaluated clinical and economic outcomes among acute bacterial skin and skin structure infections (ABSSSI) patients hospitalized at a 3000-bed healthcare system in New Jersey.

RESEARCH DESIGN AND METHODS

In this retrospective cohort analysis, adult ABSSSI patients hospitalized between July 2010 and December 2011 were stratified based on infection type: cellulitis/erysipelas and major cutaneous abscess, wound infection, and all ABSSSI. Initial antibiotic therapy was assessed by individual agent, regimen, and MRSA coverage. Day 3 response to initial antibiotic therapy was evaluated based on temperature and lesion cessation outcomes; clinical response rates were assessed by initial therapy and pathogen for each cohort. The impact of response on length of stay (LOS), cost of care, and antibiotic treatment duration were also evaluated.

RESULTS

Commonly used antibiotics included vancomycin, cefazolin, piperacillin-tazobactam, and ampicillin-sulbactam; over 40% of patients received empiric therapy with activity against MRSA. Clinical non-response to initial antimicrobial therapy at Day 3 was 39.9%, 30.3%, and 60.7%, for all ABSSSI, cellulitis/abscess, and wound infection patients, respectively. The cost of care among non-responders was over 1.5 times that of responders (p < 0.0001). Non-response to initial therapy was associated with a 3.7 day increase in duration of antibiotic treatment (p < 0.0001).

CONCLUSIONS

Results of this study demonstrate that a significant percentage of ABSSSI patients, particularly those with wound infection, were not achieving clinical response at Day 3 of therapy. Failure to respond to drug therapy is associated with substantial increases in LOS, antibiotic treatment duration, and cost of care.

LIMITATIONS

This had the inherent limitations associated with a retrospective chart review; because data was initially collected for clinical rather than research purposes, certain information may have been absent, incomplete, or missed by data abstractors.

Initial treatment failure in patients with complicated skin and skin structure infections

BACKGROUND

Consequences of initial antibiotic failure in patients hospitalized for complicated skin and skin-structure infections (cSSSI) are not well understood.

METHODS

Using data from >100 hospitals in the United States, we identified all adults hospitalized for cSSSI between January 1, 2000 and June 30, 2009. We defined "initial therapy" as all parenteral antibiotics administered <24 h of admission, and such therapy was assumed to have failed if the patient (1) received new antibiotic(s) subsequently (excluding similar/narrower spectrum antibiotics or those begun at discharge), or (2) underwent drainage/debridement/amputation>72 h after admission. We limited attention to the 40 most commonly used antibiotic regimens in 2009. We compared clinical and economic outcomes of patients who experienced initial treatment failure and those who did not.

RESULTS

The rate of initial treatment failure was 16.6% in acute infections (n=13,498), 34.1% in chronic/ulcerative infections (n=1,116), and 26.7% in surgical site infections (SSIs) (n=2,929). Treatment failure was associated with 4.1-7.3 additional days in the hospital and $11,995-$23,655 in additional inpatient charges; the case fatality rate was from 4- to 12-fold higher in patients who experienced treatment failure than in those who did not (all comparisons, p<0.01).

CONCLUSION

Initial treatment failure in patients hospitalized for cSSSI is associated with significantly worse clinical outcomes, longer hospital stays, and higher hospital charges than with successful initial treatment.

The efficacy and safety of arbekacin and vancomycin for the treatment in skin and soft tissue MRSA infection: preliminary study

Background

Methicillin-resistant Staphylococcus aureus (MRSA) has become a one of the most important causes of nosocomial infections, and use of vancomycin for the treatment of MRSA infection has increased. Unfortunately, vancomycin-resistant enterococcus have been reported, as well as vancomycin-resistant S. aureus. Arbekacin is an antibacterial agent and belongs to the aminoglycoside family of antibiotics. It was introduced to treat MRSA infection. We studied the clinical and bacteriological efficacy and safety of arbekacin compared to vancomycin in the treatment of infections caused by MRSA.

Materials and Methods

This was a retrospective case-control study of patients who were admitted to tertiary Hospital from January 1st, 2009 to December 31st, 2010, and received the antibiotics arbekacin or vancomycin. All the skin and soft tissue MRSA infected patients who received arbekacin or vancomycin were enrolled during the study period. The bacteriological efficacy response (BER) was classified with improved and failure. The improved BER was defined as no growth of MRSA, where failure was defined as growth of MRSA, culture at the end of therapy or during treatment. Clinical efficacy response (CER) was classified as improved and failure. Improved CER was defined as resolution or reduction of the majority of signs and symptoms related to the original infection. Failure was defined as no resolution and no reduction of majority of the signs and symptoms, or worsening of one or more signs and symptoms, or new symptoms or signs associated with the original infection or a new infection.

Results

Totally, 122 patients (63/99 in arbekacin, 59/168 in vancomycin group) with skin and soft tissue infection who recieved arbekacin or vancomcyin at least 4 days were enrolled and analysed. The bacteriological efficacy response [improved, arbekacin vs vancomycin; 73.0% (46/63), 95% confidence interval (CI) 60.3 to 83.4% vs 83.1% (49/59), 95% CI 71.0 to 91.6%] and clinical efficacy response [improved, arbekacin vs vancomycin; 67.2% (41/61), 95% CI 52.0 to 76.7% vs 78.0% (46/59), 95% CI 65.3 to 87.7%] were similar between the two groups (P=0.264, 0.265). The complication rate was significantly higher in the vancomycin group [29/59(49.2%), 95% CI 35.9 to 62.5%] than arbekacin [10/63(15.9%), 95% CI 8.4 to 29.0%] (P<0.001).

Conclusions

Arbekacin could be considered as an alternative antibiotics for vancomycin in skin and soft tissue infection with MRSA. However, further prospective randomized trials are needed to confirm this finding.

A prospective, multicenter, observational study of complicated skin and soft tissue infections in hospitalized patients: clinical characteristics, medical treatment, and outcomes

Background

Complicated skin and soft tissue infections (cSSTIs) occur frequently, but limited data do not allow any consensus on an optimal treatment strategy. We designed this prospective, multicenter, observational study to to explore the current epidemiology, treatment, and resulting clinical outcomes of cSSTIs to help develop strategies to potentially improve outcomes.

Methods

From June 2008 to December 2009 we enrolled a pre-specified number of adults treated in 56 U.S. hospitals with intravenous antibiotic(s) for any of the following cSSTIs: diabetic foot infection (DFI); surgical site infection (SSI); deep soft tissue abscess (DSTA); or, cellulitis. Investigators treated all patients per their usual practice during the study and collected data on a standardized form.

Results

We enrolled 1,033 patients (DFI 27%; SSI 32%; DSTA 14%; cellulitis 27%; mean age 54 years; 54% male), of which 74% had healthcare-associated risk factors. At presentation, 89% of patients received initial empiric therapy with intravenous antibiotics; ~20% of these patients had this empiric regimen changed or discontinued based on culture and sensitivity results. Vancomycin was the most frequently used initial intravenous antibiotic, ordered in 61% of cases. During their stay 44% of patients underwent a surgical procedure related to the study infection, usually incision and drainage or debridement. The mean length of stay was 7.1 days, ranging from 5.8 (DSTA) to 8.1 (SSI).

Conclusion

Our findings from this large prospective observational study that characterized patients with cSSTIs from diverse US inpatient populations provide useful information on the current epidemiology, clinical management practices and outcomes of this common infection.

Toward new therapeutics for skin and soft tissue infections: propargyl-linked antifolates are potent inhibitors of MRSA and Streptococcus pyogenes

Hospital- and community-acquired, complicated skin and soft tissue infections, often attributed to Staphylococcus aureus and Streptococcus pyogenes, present a significant health burden that is associated with increased health care costs and mortality. As these two species are difficult to discern on diagnosis and are associated with differential profiles of drug resistance, the development of an efficacious antibacterial agent that targets both organisms is a high priority. Herein we describe a structure-based drug development effort that has produced highly potent inhibitors of dihydrofolate reductase from both species. Optimized propargyl-linked antifolates containing a key pyridyl substituent display antibacterial activity against both methicillin-resistant S. aureus and S. pyogenes at MIC values below 0.1 µg/mL and minimal cytotoxicity against mammalian cells. Further evaluation against a panel of clinical isolates shows good efficacy against a range of important phenotypes such as hospital- and community-acquired strains as well as strains resistant to vancomycin.

A randomized trial of the efficacy and safety of sequential intravenous/oral moxifloxacin monotherapy versus intravenous piperacillin/tazobactam followed by oral amoxicillin/clavulanate for complicated skin and skin structure infections

OBJECTIVES

The primary aim of the RELIEF study was to evaluate the efficacy and safety of two sequential intravenous (iv)/oral regimens: moxifloxacin iv/oral versus piperacillin/tazobactam (TZP) iv followed by oral amoxicillin/clavulanate (AMC).

PATIENTS AND METHODS

The study had a prospective, randomized, double-dummy, double-blind, multicentre design. Patients ≥18 years were prospectively stratified according to complicated skin and skin structure infection (cSSSI) subtype/diagnosis (major abscess, diabetic foot infection, wound infection or infected ischaemic ulcer), surgical intervention and severity of illness. Diagnoses and disease severity were based on predetermined criteria, documented by repeated photographs, and confirmed by an independent data review committee. Patients were randomized to receive either 400 mg of moxifloxacin iv once daily followed by 400 mg of moxifloxacin orally once daily or 4.0/0.5 g of TZP iv thrice daily followed by 875/125 mg of AMC orally twice daily for 7-21 days. The primary efficacy variable was clinical response at test of cure (TOC) for the per-protocol (PP) population. Clinical efficacy was assessed by the data review committee based on repeated photographs and case descriptions. Clinical trials registry number: NCT 00402727.

RESULTS

A total of 813 patients were randomized. Clinical success rates at TOC were similar for moxifloxacin and TZP-AMC in the PP [320/361 (88.6%) versus 275/307 (89.6%), respectively; P = 0.758] and intent-to-treat (ITT) [350/426 (82.2%) versus 305/377 (80.9%), respectively; P = 0.632] populations. Thus, moxifloxacin was non-inferior to TZP-AMC. Bacteriological success rates were high in both treatment arms [moxifloxacin: 432/497 (86.9%) versus TZP-AMC: 370/429 (86.2%), microbiologically valid (MBV) population]. Moxifloxacin was non-inferior to TZP-AMC at TOC in both the MBV and the ITT populations. Both treatments were well tolerated.

CONCLUSIONS

Once-daily iv/oral moxifloxacin monotherapy was clinically and bacteriologically non-inferior to iv TZP thrice daily followed by oral AMC twice daily in patients with cSSSIs.

Meropenem in the treatment of complicated skin and soft tissue infections

Meropenem is a broad-spectrum carbapenem antibiotic with excellent activity against many pathogens associated with complicated skin and soft tissue infections (cSSTIs). At least three studies have shown meropenem to have good clinical efficacy and to be well tolerated in the treatment of cSSTIs. Two open-label studies compared meropenem 500 mg every 8 hours (total evaluable n=146) with imipenem/cilastatin 500mg every 6 hours (n=147). Clinical efficacy rates in evaluable patients 7–14 days after end of treatment were similar, 92% and 100% in meropenem-treated groups versus 89% and 100% in groups receiving imipenem/cilastatin. An additional prospective, randomized, double-blind study evaluated meropenem 500mg every 8 hours (261 evaluable patients) versus imipenem/cilastatin 500 mg every 8 hours (287 patients). Clinical efficacy rates of meropenem and imipenem/cilastatin 7–28 days after end of treatment were 86.2% and 82.9%, respectively. Meropenem was well tolerated in all studies. Carbapenems are currently recommended as appropriate for initial treatment of certain cSSTIs such as those likely to involve mixed and/or multidrug-resistant pathogens. Meropenem is an effective and safe alternative for monotherapy when used for appropriate types of cSSTIs. Higher doses (ie, 1 g every 8 hours) should be considered for treatment of cSSTIs in higher-risk patients where Pseudomonas aeruginosa is a suspected or documented pathogen.

Detection of the macrolide-efflux protein A gene mef(A) in Enterococcus faecalis

The mef(A) gene codes for an efflux protein that conveys resistance to 14- and 15-membered macrolides. Enterococci are emerging pathogens, as well as indicator and reservoir bacteria that are known to have a strong tendency to acquire resistance genes. A total of 485 Enterococcus faecalis strains of porcine (n = 239) and human origin (n = 246) were screened for the presence of the mef(A) gene by using polymerase chain reaction. In total, 29 E. faecalis of porcine (n = 10) and human (n = 19) origin were positive for the presence of the mef(A) gene. Most of the mef(A)-containing strains were isolated from fecal samples of healthy individuals; only one strain originated from a stool sample of a diseased pig. To our knowledge, this is the first report on the occurrence of the mef(A) gene in E. faecalis apart from mating experiments. The main clinical relevance of this study is that donor E. faecalis might transfer the mef(A) gene to recipients that are usually combated with macrolides. Hence, the role of E. faecalis as a resistance reservoir with respect to limited treatment options are a cause for concern.

[Management of soft tissue infections in the region of the extremities and the trunk]

Skin and soft tissue infections (SSTI) are amongst the most common bacterial infections in humans. SSTI have a broad range of aetiology, clinical manifestation and severity. The outcome may be spontaneous resolution or on the other end sepsis with lethal outcome. Useful classifications are those which differentiate SSTI according to urgency of surgical intervention. The definitive diagnosis should be made by the clinical picture of the lesion and the condition of the patient. The key to successful treatment of many severe necrotizing soft tissue infections is based on early detection and prompt surgical debridement. This procedure has to be followed by an optimal wound management. From the early beginning of treatment an adequately calculated antibiotic treatment is mandatory. At the end of the treatment the wound has to be closed by an aesthetic scar with high mechanical load capacity.

Prospective, non-comparative study of daptomycin for the treatment of superficial and deep incisional surgical site infections

BACKGROUND

Skin infections, including surgical site infections (SSIs), usually involve gram-positive pathogens and continue to be a leading cause of morbidity and death among hospital patients. The increasing prevalence of methicillin-resistant Staphylococcus aureus and other resistant strains accentuates the need for effective and safe therapies for such infections. This exploratory study evaluated the efficacy and safety of daptomycin in patients with gram-positive SSI according to wound classification.

METHODS

Eligible patients had an SSI with onset < 30 days after surgery, positive gram stain or culture at least three days before daptomycin therapy began, and three or more clinical signs and symptoms of infection. The incisional SSI was classified as superficial or deep according to the U.S. Centers for Disease Control and Prevention criteria. Patients with organ-space infections were excluded, as were those with major concomitant infections, foreign material in the incision that could not be removed, previous systemic antimicrobial therapy, or creatinine clearance < 30 mL/min. Daptomycin 4 mg/kg was administered intravenously once daily for 7-14 days. The primary efficacy endpoint was clinical response at the end of daptomycin therapy, and the safety assessment was based on adverse events (AEs).

RESULTS

Sixty-nine patients were enrolled, 60 of whom were evaluable for efficacy. Extremity wounds predominated among superficial incisional SSIs (n = 30), whereas abdominal wounds predominated among deep SSIs (n = 30). Patients with deep incisional SSI were more likely to be young, male, white, and febrile and to weigh more than patients with superficial SSIs. The overall clinical success rate was 92% (95% confidence interval [CI] 82-97%); the success rate was 100% in superficial incisional SSI and 83% in deep SSI (17% difference; 95% CI 0-33%). Staphylococcus aureus (28/36 methicillin-resistant) was the pathogen isolated most frequently. In 10 patients who were febrile at baseline, the median time to defervescence was five days, and the mean duration of treatment in the series was 11.2 days. Daptomycin was well tolerated. In most patients, AEs were mild or moderate in intensity; in two patients (one superficial, one deep), daptomycin was discontinued because of AEs.

CONCLUSIONS

The results of this exploratory study of SSI are consistent with those of previous studies of daptomycin in the treatment of diverse complicated skin and skin-structure infections, and suggest that wound classification should be treated as an important covariate in future studies of daptomycin and other antibiotics.

Resistance and the management of complicated skin and skin structure infections: the role of ceftobiprole

Antimicrobial resistant bacteria are an increasing concern due to the resulting increase in morbidity, mortality, and health-care costs associated with the administration of inadequate or delayed antimicrobial therapy. The implications of inadequate antimicrobial therapy in complicated skin and skin structure infections (cSSSIs) have gained more attention recently, most likely due to the recent emergence of community-acquired methicillin resistant Staphylococcus aureus (MRSA) and the already high prevalence of MRSA in the nosocomial setting. Due to the continuous threat of resistance arising and the limitations of currently available agents for the treatment of cSSSIs, it is necessary to develop new antimicrobials for this indication. Ceftobiprole medocaril, the prodrug of ceftobiprole, is a parental investigational cephalosporin for the treatment of cSSSIs displaying a wide-spectrum of activity against both Gram-positive and Gram-negative species, including MRSA. Ceftobiprole displays noncomplex linear pharmacokinetics, is eliminated primarily by glomerular filtration, and distributes to extracellular fluid. Additionally, it has been shown that the extent of distribution to the site of action with regard to cSSSIs, ie, the extracellular space fluid of subcutaneous adipose tissue and skeletal muscle, is expected to be efficacious, as free concentrations meet efficacy targets for most pathogens. Similar to other beta-lactams, it displays an excellent safety and tolerability profile with the primary adverse events being dysgeusia in healthy volunteers, resulting from the conversion of the prodrug to the active, and nausea in patients. Ceftobiprole has demonstrated noninferiority in two large-scale pivotal studies comparing it to vancomycin, clinical cure rates 93.3% vs 93.5%, respectively, or vancomycin plus ceftazidime, clinical cure rates 90.5% vs 90.2%, respectively. Given the pharmacokinetic and pharmacodynamic properties, ceftobiprole is a promising new agent for the treatment of cSSSIs and has the potential to be used as a single agent for empiric treatment.

Antibiotic optimization in the difficult-to-treat patient with complicated intra-abdominal or complicated skin and skin structure infections: focus on tigecycline

Complicated intra-abdominal and skin and skin structure infections are widely varied in presentation. These infections very often lead to an increase in length of hospital stay, with a resulting increase in costs and mortality. In addition, these infections may be caused by a wide variety of bacteria and are often polymicrobial with the possibility of the presence of antimicrobial-resistant strains, such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, extended-spectrum β-lactamase strains (Escherichia coli, Klebsiella pneumoniae), and K. pneumoniae carbapenemase-producing strains. In combination with patients’ immunosuppression or comorbidities, the treatment and management options for initial therapy success are few. Tigecycline, a new glycylcyline antimicrobial from the tetracycline drug class, represents a viable option for the successful treatment of these infections. It has been shown to have activity against a wide variety of bacteria, including the antimicrobial-resistant strains. As with all tetracycline drugs, it is not recommended for pregnant or nursing women. The potential side effects are those typical of tetracycline drugs: nausea, vomiting, and headaches. Drug–drug interactions are not expected, and renal function monitoring is not necessary.

Kinetic analysis and modeling of daptomycin batch fermentation by Streptomyces roseosporus

In this study, Streptomyces roseosporus was subjected to helium-neon (He-Ne) laser (632.8 nm) irradiation to improve the production ability of extracellular antibiotic daptomycin. Under the optimum irradiation dosage of 18 mW for 22 min, a stable positive mutant strain S. roseosporus LC-54 was obtained. The maximum A21978C (daptomycin is a semisynthetic antimicrobial substance derived from the A21978C complex) yield of this mutant strain was 296 mg/l, which was 146% higher than that of the wild strain. The mutant strain grew more quickly and utilized carbohydrate sources more efficiently than the wild strain. The batch culture kinetics was investigated in a 7 l bioreactor. The logistic equation for growth, the Luedeking-Piret equation for daptomycin production, and Luedeking-Piret-like equations for carbon substrate consumption were established. This model appeared to provide a reasonable description for each parameter during the growth phase and fitted fairly well with the experiment data.

High frequency of macrolide resistance mechanisms in clinical isolates of Corynebacterium species

The genus Corynebacterium includes a high number of species that are usually isolated from human skin as saprophytes. However, these microorganisms have also been reported as infectious agents in a broad group of patients and have showed broad-spectrum resistance. We studied the susceptibility profiles against macrolides, clindamycin, and streptogramins of 254 clinical strains belonging to the species Corynebacterium urealyticum (120), Corynebacterium amycolatum (66), Corynebacterium jeikeium (17), Corynebacterium striatum (20), Corynebacterium coyleae (12), Corynebacterium aurimucosum (11), and Corynebacterium afermentans subsp. afermentans (8). The MLS(B) phenotype was detected in 186 strains and was associated with the presence of methylase enzymes codified by the erm(X) gene in 171 strains. The erm(B) gene was only detected in two C. urealyticum strains. Fourteen strains showed macrolide resistance, but they did not carry erm genes. mef genes were not detected despite eight C. amycolatum strains showed the M phenotype. Also, the presence of hydrolytic enzymes codified by ere(B) was evaluated, but all results were negative. Resistance to macrolide in Corynebacterium sp. is mainly due to the presence of erm(X) methylase, although other resistance mechanisms could be involved.

Efficacy and safety of linezolid in methicillin-resistant Staphylococcus aureus (MRSA) complicated skin and soft tissue infection (cSSTI): a meta-analysis

OBJECTIVE

To evaluate the clinical and microbiological outcomes of linezolid versus vancomycin in methicillin-resistant Staphylococcus aureus (MRSA) complicated skin and soft-tissue infection (cSSTI) using a meta-analysis.

RESEARCH DESIGN AND METHODS

Clinical trials were identified using PubMed, the Cochrane Central Register of Controlled Trials, and the International Pharmaceutical Abstracts from inception to March 2009. Primary outcomes evaluated resolution of signs and symptoms of infection in clinically evaluable (CE) patients, and microbiological eradication in both the modified intent-to-treat (MITT) and MRSA evaluable (MRSA ME) patients. MITT patients had a culture-confirmed Gram-positive pathogen (S. aureus) at baseline. Secondary outcomes included mortality, adverse drug reactions (ADR), and discontinuation due to ADRs. The Mantel-Haenszel odds ratios (OR) with 95% confidence intervals (CI) were calculated using the fixed effects model based on the assumption that there was little to no heterogeneity between the studies in the primary analysis. Sensitivity analyses were performed for each outcome by removing the most weighted study.

RESULTS

Five studies with a total of 2652 patients (1361/linezolid; 1291/vancomycin) were identified. Resolution of infection in CE patients (OR = 1.41; 95% CI: 1.03, 1.95) and MITT patients (OR = 1.91; 95% CI: 1.33, 2.76) favored the use of linezolid over vancomycin, but did not remain significant after sensitivity analyses (CE: OR = 1.29; 95% CI: 0.81, 2.05; MITT: OR = 1.73; 95% CI: 0.87, 3.41). Microbiological eradication in MRSA ME patients consistently favored the use of linezolid over vancomycin (OR = 2.90; 95% CI: 1.90, 4.41). No difference in mortality was observed between the two groups (OR = 1.17; 95% CI: 0.85, 1.62). Higher proportions of linezolid patients were found to have diarrhea (119/1361 vs. 52/1291), nausea (102/1361 vs. 46/1291) and thrombocytopenia (54/1121 vs. 8/1071), whereas a higher proportion of vancomycin patients were found to have renal insufficiency compared to linezolid (16/634 vs. 4/703). Inconsistent results were seen with the incidence of anemia and rash between the base-case (anemia: OR = 1.36; 95% CI: 0.90, 2.08; rash: OR = 0.26; 95% CI: 0.10, 0.68) and sensitivity analyses (anemia: OR = 2.33; 95% CI: 1.24, 4.37; rash: OR = 0.57; 95% CI: 0.12, 2.71). Discontinuation due to ADRs was not statistically different between linezolid and vancomycin (OR = 1.06; 95% CI: 0.75, 1.51).

CONCLUSION

Resolution of infection in CE and MITT patients were inconsistent; however, a sub-analysis revealed that linezolid was more likely to consistently achieve microbiologic eradication in MRSA ME patients. Apparent risks of thrombocytopenia, nausea, diarrhea, and possibly anemia may limit linezolid use in treating MRSA cSSTI. This study was limited due to an inability to assess for the effects of hetero-resistance and appropriate vancomycin dosing on outcomes. Moreover, the small number of studies made controlling for heterogeneity challenging.

Inpatient treatment patterns, outcomes, and costs of skin and skin structure infections because of Staphylococcus aureus

BACKGROUND

Staphylococcus aureus (SA) is a common bacterial pathogen in skin and skin structure infections (SSSIs). Limited data exist on hospital treatment patterns and costs for SA-SSSIs.

METHODS

This retrospective analysis examined the lengths of stay, treatment patterns, and costs of hospitalized patients with an SA-SSSI diagnosis using a nationally representative inpatient database. Patients were selected if they had an ICD-9-CM diagnosis of an SSSI with SA noted between January 2005 and June 2006, received a study antibiotic (ie, intravenous [IV] vancomycin, IV or oral linezolid, and IV daptomycin), and were not in the intensive care unit before receiving a study antibiotic. Generalized linear models assessed predictors of length of stay and costs. Costs are expressed in 2005 US dollars.

RESULTS

Thirteen thousand four hundred thirty-three patients met the selection criteria and mean (+/-SD) age was 48.2 (+/-18.3) years. Forty percent of patients received a nonstudy antibiotic before receiving their first study antibiotic. Ninety-five percent were prescribed vancomycin as their first study antibiotic. Study antibiotics were administered for an average of 4.3 days, and 8% of patients switched study antibiotics. Nineteen percent of patients receiving IV linezolid stepped down to oral linezolid. Mean (+/-SD) lengths of hospital stay and costs were 6.1 (+/-6.0) days and $6830 (+/-$7100). In-hospital mortality, switching antibiotics, and diagnoses of selected complications or comorbidities were associated with increased lengths of stay and costs. Younger age, location outside the Northeast, and use of oral linezolid were associated with lower lengths of stay and costs.

CONCLUSION

The costs of treating inpatient SA-SSSIs are substantial and vary by patient demographics and treatment characteristics.

Multicenter, randomized study of the efficacy and safety of intravenous iclaprim in complicated skin and skin structure infections

Iclaprim is a novel antibacterial agent that is currently in development for the treatment of complicated skin and skin structure infections (cSSSI). Iclaprim specifically and selectively inhibits bacterial dihydrofolate reductase, a critical enzyme in the bacterial folate pathway, and exhibits an extended spectrum of activity against various resistant pathogens, including methicillin (meticillin)-resistant Staphylococcus aureus (MRSA). The objective of this randomized, double-blind phase II study was to compare the efficacy and safety of iclaprim to those of vancomycin in patients with cSSSI. Patients were randomized to receive 0.8 mg iclaprim/kg of body weight, 1.6 mg/kg iclaprim, or 1 g vancomycin twice a day for 10 days. Clinical cure rates for the 0.8- and 1.6-mg/kg-iclaprim treatment groups were comparable to that for the vancomycin treatment group (26/28 patients [92.9%], 28/31 patients [90.3%], and 26/28 patients [92.9%], respectively). Iclaprim also showed high microbiological eradication rates. Iclaprim exhibited an eradication rate of 80% and 72% versus 59% observed with vancomycin for S. aureus, the pathogen most frequently isolated at baseline. Five MRSA cases were observed, four in the 0.8-mg/kg-iclaprim arm and one in the vancomycin arm, and all were both clinically and microbiologically cured. Iclaprim exhibited a safety profile similar to that of vancomycin, an established drug for the treatment of cSSSI. Results from this study indicate that iclaprim is a promising new therapy for the treatment of cSSSI, in particular those caused by S. aureus, including MRSA.

Review of the guidelines for complicated skin and soft tissue infections and intra-abdominal infections--are they applicable today?

Difficult-to-treat infections in surgical patients, such as serious skin and soft tissue infections (SSTIs) and complicated intra-abdominal infections (cIAIs), are the cause of significant morbidity and mortality, and carry an economic burden. These surgical site infections are typically polymicrobial infections caused by a plethora of pathogens, which include difficult-to-treat organisms and multiresistant Gram-positive and Gram-negative strains. Optimal management of SSTIs and cIAIs must take into account the presence of resistant pathogens, and depends on the administration of appropriate antimicrobial therapy (i.e. the correct spectrum, route and dose in a timely fashion for a sufficient duration as well as the timely implementation of source control measures). Treatment recommendations from the Infectious Diseases Society of America and the Surgical Infection Society are available for guidance in the management of both of these infections, yet the increased global prevalence of multidrug-resistant pathogens has complicated the antibiotic selection process. Several pathogens of concern include methicillin-resistant Staphylococcus aureus, responsible for problematic postoperative infections, especially in patients with SSTIs, extended-spectrum beta-lactamase-producing Gram-negative bacteria, including CTX-M-type-producing Escherichia coli strains, and multidrug-resistant strains of Bacteroides fragilis. New empirical regimens, taking advantage of potent broad-spectrum antibiotic options, may be needed for the treatment of certain high-risk patients with surgical site infections.

Costs of skin and skin structure infections due to Staphylococcus aureus: an analysis of managed-care claims

OBJECTIVES

The incidence of skin and skin structure infections (SSSIs) due to Staphylococcus aureus (SA) is increasing. The objective of this study was to assess the costs of a treatment episode for SA-SSSIs.

METHODS

This retrospective analysis used a managed-care claims database to assess the duration and costs of incident SA-SSSI episodes treated with selected antibiotics (i.v. vancomycin, oral linezolid, and daptomycin, termed 'study antibiotics'). Patients were included if they had an ICD-9-CM diagnosis of an SSSI and SA between January 1, 2002 and December 31, 2005. Treatment episodes began on the date of the first antibiotic and ended when the patient had fourteen consecutive days without a study antibiotic or SSSI hospitalization. Costs, represented by health plan payments for SSSIs and overall, were updated to 2005 US dollars. A generalized linear model (GLM) assessed predictors of costs.

RESULTS

A total of 1997 patients met the selection criteria. Mean (+/- SD) age was 46.3 (+/- 12.6) years and 55.9% of patients were male. Average episode length was 24 days, and over 95% of patients received i.v. vancomycin or oral linezolid as their initial study antibiotic. Patients remained on study antibiotics for an average of 16.4 days, and only 5% of patients were switched to another study antibiotic. Mean (+/- SD) overall episode costs were $8865 (+/- $20,003), primarily composed of inpatient and outpatient medical services. Treatment failure (i.e., study antibiotic switching or hospitalization), younger age, a diagnosis of bacteremia, osteomyelitis, or multiple complications during the episode, treatment with daptomycin, and greater Charlson co-morbidity score were significant positive predictors of overall costs. Alternatively, treatment with oral linezolid and hospitalization before the start of the outpatient treatment episode were significant negative predictors of overall costs. Mean (+/- SD) SSSI-related costs were $4551 (+/- $11,058).

LIMITATIONS

Medical charts and laboratory test results were not available to confirm SSSI and SA diagnoses, and no information was available regarding antibiotics received in the inpatient setting.

CONCLUSIONS

The costs of treating SA-SSSIs are substantial and vary by failure rates, co-morbidities, and type of antibiotic therapy.

A pilot study of high-dose short duration daptomycin for the treatment of patients with complicated skin and skin structure infections caused by gram-positive bacteria

BACKGROUND

Methicillin-susceptible and -resistant (MRSA) Staphylococcus aureus are significant causes of complicated skin and skin structure infections (cSSSI). The bactericidal antibiotic daptomycin is approved for gram-positive cSSSI at 4 mg/kg/day for 7-14 days, but the optimal dose level and duration of therapy have not been firmly established. This pilot study evaluated the efficacy and safety of daptomycin at 10 mg/kg every 24 h for 4 days [high-dose short duration (HDSD) regimen] vs. standard of care therapy with vancomycin or semi-synthetic penicillin for the treatment of cSSSI.

METHODS

This was a semi-single blind, randomised, multicentre, comparative trial. The primary efficacy end-point was the clinical response 7-14 days posttherapy.

RESULTS

One hundred patients were randomised; 48 in each arm were treated. The treatment groups were well balanced with respect to demographics, comorbidities and the type of infection (75% because of MRSA). Overall, clinical success rates were 75.0% (36/48) for daptomycin and 87.5% (42/48) for comparator (95% confidence interval for the difference: -27.9, 2.9). The median duration of comparator therapy was 8 days. Two comparator patients and no daptomycin patients experienced treatment-related serious adverse events requiring hospitalisation.

CONCLUSION

We found that the HDSD regimen had a safety profile similar to that seen in previous studies. Although the differences were not statistically significant, clinical success rates for comparator were higher than for daptomycin. In post hoc analyses HDSD daptomycin performed better in some subgroups (e.g. outpatients) than in others (e.g. certain MRSA infections). These observations require confirmation in larger trials.

How complicated skin and soft tissue infections are treated in Italy: economic evaluation of inpatient intravenous antibiotic treatment in seven hospitals

OBJECTIVES

Complicated skin and soft tissue infections (cSSTIs) are a common cause of morbidity at hospital level. This study aimed to evaluate the costs and outcomes of inpatient intravenous antibiotic therapy for the treatment of cSSTI in seven Italian hospitals.

METHODS

A total of 307 patients were enrolled in a retrospective, multicentre, incidence-based, observational study. The target population consisted of hospitalised patients eligible to receive intravenous antibiotic therapy for cSSTI. Direct hospital costs were measured through a microcosting approach.

RESULTS

Failure of initial antibiotic therapy occurred in 23% of patients. Average antibiotic treatment lasted 12.2 days; the average full cost of admission totalled euro5,530. If the initial antibiotic regimen fails to eradicate the infectious organism, the length of stay extends for 7 days and costs increase by euro2,850 per patient. Nevertheless, when taking into account the lower intensity of care during the last days of treatment, savings reduce costs to euro671 per patient. These could be increased by euro74 for each hospital day avoided because of faster antibiotic action.

CONCLUSIONS

Efforts should be made to minimise the risk of selecting wrong antibiotics and to identify the quickest antibiotic in eradicating the infection.

Postmarketing clinical experience in patients with skin and skin-structure infections treated with daptomycin

A registry describing daptomycin's clinical use was analyzed to describe treatment of skin and skin-structure infections (SSSIs). The Cubicin Outcomes Registry and Experience (CORE) 2004 retrospectively collected demographic, microbiologic, and clinical outcome information of patients treated with daptomycin (Cubicin; Cubist Pharmaceuticals, Inc., Lexington, MA). The database was accessed to identify patients with a diagnosis of an SSSI with an outcome determined. Of 577 patients identified with a SSSI, 522 (90%) were evaluable. Diabetes mellitus and peripheral vascular disease were present in 27% and 10% of the population, respectively. Pathogens were identified for 65% of all patients-Staphylococcus aureus (75%; 85% methicillin-resistant) and Enterococcus species (19%; 44% vancomycin-resistant) most commonly. Concomitant use of other antibiotics was common (42%). Of 522 patients studied, 334 (64%) had complicated infections (cSSSIs), and 188 (36%) had uncomplicated infections (uSSSIs). Overall cure, improved, and failure rates were 53%, 43%, and 4%, respectively, for cSSSI and 66%, 32%, and 2%, respectively, for uSSSI. The median dose administered was 4.0 mg/kg for cSSSI (mean, 4.5+/-1.0 mg/kg; range, 2.3 to 12 mg/kg) and 4.0 mg/kg for uSSSI (mean, 4.2+/-0.8 mg/kg; range, 2.1 to 9 mg/kg); the dose was significantly higher in cSSSI (P <0.001, median test). Median daptomycin treatment duration was 12 days (range, 1 to 148 days) and was longer for cSSSI than for uSSSI (14 vs. 10 days, P = 0.002). The results of this study support previously published reports and suggest that daptomycin is effective for the treatment of skin infections due to gram-positive pathogens.

Skin and skin structure infections: treatment with newer generation fluoroquinolones

Skin and skin structure infections (SSSI) are an emerging issue in healthcare. They are responsible for increasing heathcare utilization, both in hospitalizations and intravenous antibiotic use. SSSI are caused by an evolving variety of pathogens, including Gram-positive, Gram-negative, and anaerobic bacteria. In combination with mounting resistance patterns, this diverse range of bacteria mandate empiric broad-spectrum antibiotic coverage. Historically, cephalosporins and penicillins have been the mainstay of treatment, but recent data suggest newer generation fluoroquinolones are being used with increasing frequency. In 2005, moxifloxacin joined gatifloxacin and levofloxacin as newer generation fluoroquionolones with Food and Drug Administration indications for SSSIs. Even within this group there exist subtle differences that impact optimal management. This paper offers the clinician a comparative review of the antimicrobial spectrum, pharmacodynamics, pharmacokinetics, and clinical efficacy data to support the appropriate use of fluoroquinolones in SSSIs.

Exposure-response analyses of tigecycline efficacy in patients with complicated skin and skin-structure infections

Exposure-response analyses were performed for the microbiological and clinical efficacy of tigecycline in the treatment of complicated skin and skin-structure infections, where Staphylococcus aureus and streptococci are the predominant pathogens. A prospective method was developed to create homogeneous patient populations for PK-PD analyses. Evaluable patients from three clinical trials were pooled for analysis. Patients received a tigecycline 100-mg loading dose/50 mg every 12 h or a 50-mg loading dose/25 mg every 12 h. At the test-of-cure visit, microbiologic and clinical responses were evaluated. Patients were prospectively evaluated and classified into cohorts based on baseline pathogens: S. aureus only (cohort 1), monomicrobial S. aureus or streptococci (cohort 2), two gram-positive pathogens (cohort 3), polymicrobial (cohort 4), or other monomicrobial infections (cohort 5). A prospective procedure for combining cohorts was used to increase the sample size. Logistic regression evaluated steady-state 24-h area under the concentration-time curve (AUC(24))/MIC ratio as a predictor of response, and classification and regression tree (CART) analyses were utilized to determine AUC/MIC breakpoints. Analysis began with pooled cohorts 2 and 3, the focus of these analyses, and included 35 patients with 40 S. aureus and/or streptococcal pathogens. CART analyses identified a significant AUC/MIC breakpoint of 17.9 (P = 0.0001 for microbiological response and P = 0.0376 for clinical response). The continuous AUC/MIC ratio was predictive of microbiological response based on sample size (P = 0.0563). Analysis of all pathogens combined decreased the ability to detect exposure-response relationships. The prospective approach of creating homogeneous populations based on S. aureus and streptococci pathogens was critical for identifying exposure-response relationships.

Determination of the antibacterial efficacy of a new porphyrin-based photosensitizer against MRSA ex vivo

Following extensive in vitro screening of new photosensitizers the purpose of the present study was to examine penetration as well as antibacterial efficacy of a lead photosensitizer against MRSA using an ex vivo porcine skin model. Two different applications were performed: (i) preincubation of bacteria in solution with a porphyrin-based photosensitizer XF73 and subsequent application on the ex vivo porcine skin; (ii) application of pure bacteria on the explants followed by an incubation with XF73 in a water-ethanol formulation for up to 60 min under occlusion. The localisation of XF73 was restricted to the stratum corneum. Different concentrations (0-10 microM) of XF73 and different incubation times (5-60 min) were used to determine phototoxicity against methicillin-resistant and methicillin-sensitive S. aureus, which was applied on the explants. Preincubation of S. aureus with 0.1 microM XF73 in solution prior to the application of these XF73-incubated bacteria on the skin demonstrates a higher efficacy (>3 log10) after irradiation. Antibacterial photodynamic inactivation resulted in a approximately 1 log10 (0.1 microM)-3.64+/-0.035 (10 microM) log10 growth reduction independently of the antibiotic resistance pattern of used S. aureus strains. Irradiation of applied bacteria without photosensitizer incubation did not show any marked decrease (<1 log10) of bacteria cell number, indicating a significant phototoxicity of the XF73. Histological evaluations of untreated and treated skin areas upon irradiation within 24 h showed no significant degree of necrosis or apoptosis determined by TUNEL-assay indicating that the porcine skin is still vital. This study demonstrates that this XF73 porphyrin-based photosensitizer had concentration-dependent differences in killing efficacy of MRSA in comparison to skin cells using an ex vivo porcine skin model. The results described here imply that topical delivery of XF73 may be considered as a possible treatment in patients with superficial infections of the skin.

Antistaphylococcal activity of DX-619 alone and in combination with vancomycin, teicoplanin, and linezolid assessed by time-kill synergy testing

Time-kill synergy studies testing in vitro activity of DX-619 alone and with added vancomycin, teicoplanin, or linezolid against 101 Staphylococcus aureus strains showed synergy between DX-619 and teicoplanin at 12 to 24 h in 72 strains and between DX-619 and vancomycin in 28 strains. No synergy was found with linezolid, and no antagonism was observed with any combination.

Efficacy of daptomycin in complicated skin and skin-structure infections due to methicillin-sensitive and -resistant Staphylococcus aureus: results from the CORE Registry

OBJECTIVE

To characterize postmarketing clinical experience with daptomycin in treating complicated skin and skin-structure infections (cSSSIs) due to culture-confirmed MRSA and MSSA in real-life prescribing situations.

RESEARCH DESIGN AND METHODS

The Cubicin Outcomes Registry and Experience 2004 (CORE 2004) is a multicenter observational registry involving 45 separate institutions, designed to characterize infection types, pathogens, and outcomes of patients who were treated with daptomycin. A subset analysis of the CORE 2004 data was conducted to characterize patients with cSSSI due to culture-confirmed MRSA and MSSA, but without bacteremia, endocarditis, osteomyelitis, or other significant infectious processes. Clinical information, including patient demographics, antibiotic treatments, and clinical outcome, was analyzed. Adverse event data were not collected in CORE 2004.

MAIN OUTCOME MEASURE

Clinical success (cured or improved) or failure was assessed at the end of daptomycin treatment.

RESULTS

A total of 165 patients were identified, including 145 patients (87.9%) with MRSA and 20 patients (12.1%) with MSSA infections. Most patients received daptomycin at a dosage of 4-6 mg/kg intravenously and at a frequency of once every 24 h. Daptomycin dosing frequency was adjusted to once every 48 h or thrice weekly in all seven patients who had received hemodialysis. Prior antibiotic therapy had been administered to 121/163 (74.2%) patients and concomitant antibiotic therapy to 65/165 (39.4%) of patients. Clinical success was achieved with daptomycin in 89.1% of patients overall, including 89.7% and 85.0% of those with MRSA and MSSA, respectively. Among patients with a successful outcome, the total days of daptomycin therapy (median days: MRSA = 13.0, MSSA = 11.0) and the days to clinical response (median days: MRSA = 3.5, MSSA = 2.0) were not significantly different for MRSA and MSSA patients (p = 0.27 and p = 0.15 respectively, median test).

CONCLUSIONS

Given the limitations of this registry (which include its retrospective nature; limited numbers of MSSA patients; and lack of specific information on adverse events, type and duration of prior antibiotic therapy, timing and duration of concomitant antibiotic therapy, concomitant surgical interventions, and possible on-therapy dosing adjustments), daptomycin appeared effective in postmarketing clinical practice in the treatment of cSSSI caused by MRSA and MSSA.